1. Field of the Invention
The present invention relates to a fuel cell system and a vehicle with the fuel cell system mounted thereon.
2. Description of the Prior Art
A proposed fuel cell system includes fuel cells that generate electric power through electrochemical reactions of oxygen included in an oxidizing gas, which passes through an oxidizing gas conduit provided on a cathode side of each electrolyte membrane in a wet state, and hydrogen included in a gaseous fuel, which passes through a gaseous fuel conduit provided on an anode side of the electrolyte membrane in the wet state, a water absorbing member that is arranged in the middle of the oxidizing gas conduit, and a non-humidified gas inlet that is arranged in the middle of the oxidizing gas conduit to supply a flow of non-humidified oxidizing gas (see FIGS. 1 and 2 in Japanese Patent Laid-Open Gazette No. 6-89730). In the fuel cell system of this prior art structure, addition of the non-humidified oxidizing gas in the middle of the oxidizing gas conduit lowers the partial pressure of the water vapor and accelerates evaporation of the excess moisture. The water absorbing member absorbs condensed water and prevents the oxidizing gas conduit from being clogged by the condensed water.
In the fuel cell system of the prior art structure, the moisture in the oxidizing gas conduit is absorbed by the water absorbing member and is vaporized from the water absorbing member by the flow of non-humidified oxidizing gas to be removed from the oxidizing gas conduits. Even when there is a significantly low level of moisture in the oxidizing gas conduits, the water absorbing member works to absorb the moisture in the oxidizing gas conduit. This undesirably dries the electrolyte membrane, which is supposed to be kept in the wet state.